The invention relates to a bearing device, particularly intended for use in textile industry equipment, such as yarn feeders.
Textile industry equipment, yarn feeders or the like often have rotatably supported shafts or similar elements, with which other elements, such as yarn guide drums or the like, must be precisely supported. Relatively stringent demands commonly are made of the precision of the bearing. Furthermore, the bearings usually must be smooth-running. Preceding transmission elements, such as toothed belts or other belts, often have a relatively high resilience. If the bearings do not run smoothly constantly, then elements operatively connected to the bearings, may run unevenly, which usually cannot be tolerated.
While the demands made for bearing precision are high, still textile industry devices generally must be easy to assemble and maintain. Often, parts or housings also are made of plastic, which can shrink or swell as a consequence of aging or environmental factors (i.e., such as moisture or temperature), and furthermore, plastic parts always are subject to certain tolerances in production. Such tolerances and time- or ambient-dictated dimensional changes should not, of course, lead to a functional impairment of such devices.
From U.S. Pat. No. 5,860,298, for instance, a yarn feeder is known, in which a vertically oriented shaft is rotatably supported on a basic retainer. For bearing purposes, two ball bearings are provided, which are received in suitable cylindrical pockets of the basic carrier. The bearing seat has to adhere to close tolerances, in order to assure a good seating of the outer bearing ring. Installing and removing the bearings usually is not readily possible.
From European Patent Disclosure EP 0 742 304 A1, a yarn delivery apparatus with a horizontally divided housing is known, in which a plurality of horizontally disposed shafts that pass through the housing wall are rotatably supported. In the housing wall, bearing seats are formed, which are penetrated by the dividing seam formed between the two halves of the housing. Adaptation to production tolerances or other dimensional fluctuations is accomplished by the inherent resilience of the housing material, in conjunction with an only regional contact of the outer bearing ring with the corresponding faces of the bearing seat, by an O-ring disposed between the outer bearing ring and the bearing seat, or by special elastically resilient spring elements in the bearing seat. In this yarn feeder, the bearings are inserted from the dividing seam of the housing into the appropriate pockets with the housing open. The bearing is then firmly clamped between the housing parts. The construction is not very vulnerable to tolerances, but does require a housing seam that passes through the bearing seat.
It is an object of the invention to provide a bearing device, particularly for textile industry equipment, such as yarn feeders, which are not vulnerable to tolerances and in which the bearing can remain undivided, that is, can be in one piece.
The bearing device according to the invention has a bearing seat, which defines a receiving chamber for a roller bearing and a squeeze element. The squeeze element is squeezed together at regions spaced apart from one another, so that material of the squeeze element is positively displaced out of the squeeze zones. Regardless of any tolerances of the bearing seat, the squeeze element-secures the roller bearing nonrotatably in the bearing seat and at the same time makes it possible for the roller bearing to be inserted easily into the bearing seat. If needed, the bearing seat can therefore be made in undivided fashion.
The squeeze element can be in the form of a closed ring or as a striplike element that is put together to form a ring. It is preferably made of an elastomer. It can have either a uniform thickness throughout or locally thickened regions. Thus the squeeze zones can be defined by the shape of the bearing seat or the shape of the squeeze element. The deformation of the squeeze element locally reduces its thickness by positively displacing material. For compensation, its thickness increases in the vicinity of the compressed or squeezed region.
If the squeeze elements have thickened portions, then the bearing seat can be formed cylindrically. If the squeeze elements are uniformly thick, then the shape of the bearing seat is other than circular, so that the spacing from the roller bearing is not uniform along the circumference.
To that end, the bearing seat can be shaped polygonally or in other ways, for instance being provided with protrusions in the direction of the roller bearing. In one embodiment, the receiving chamber has ribs extending substantially parallel to the pivot axis of the roller bearing. On their side toward the roller bearing, the ribs have end faces that are located on a circle which is somewhat greater than the circle defined by the outer bearing ring of the roller bearing. Thus between the end faces and the cylindrical outer face of the roller bearing, a play arises, which is filled up by a squeeze element. This element is placed radially outward on the end faces of the ribs, while it is braced radially inward on the outer face of the outer ring. The squeeze element adjusts to the actual play present so that deviations in shape and dimension of the bearing seat and dimensional changes caused by aging, down to the range of a tenth of a millimeter, do not impair the seating of the roller bearing. Because the squeeze element contacts the ribs only in strips, the roller bearing, moreover, can be pressed with only slight impression forces axially into the bearing seat and removed from it again as needed. The squeeze element preferably rests over a large surface area on the outer face of the roller bearing so that it can be inserted with the roller bearing into the bearing seat. The static friction between the outer ring and the squeeze element prevents the squeeze element from displacement counter to the outer ring, while conversely it slides easily along the ribs, with which it has only a narrow striplike contact. This not only facilitates installation and removal but also prevents an axial warping of the roller bearing. Once the roller bearing is seated in the bearing seat, its outer ring is reliably secured against rotation. Moreover, the squeeze element cushions the outer bearing ring against the housing and compensates for deviations in shape of the bearing seat.
The receiving chamber preferably is open axially to one side to allow access to the roller bearing. If needed, the receiving chamber can be closed with a cover element.
The ribs are preferably relatively narrow, and they are disposed at a comparatively wide spacing from one another. This makes it possible for the bearings, provided with squeeze elements, to be inserted axially with only slight force into the bearing seats, yet even so a secure, precise seat of the bearing is always attained.
It is advantageous if the gaps or recesses between the ribs have a greater volume than the volume of the applicable portion of the squeeze element to be received. On the side toward the seat, the bearing is supported essentially only via the ribs. The squeeze element distributes the striplike or linear load to a somewhat larger area on the outer circumference of the roller bearing.
On the side toward the roller bearing, the ribs can have an edge or a narrow bearing face. This edge or face may be plane or curved. It is expedient to attempt to attain only a narrow linear or striplike contact face between the squeeze element and the rib. Because axial mounting is possible, the bearing seat need not have a dividing seam. The clamping force with which the bearing is retained in the bearing seat thus can be brought to bear and generated independently of fastening elements, which for instance hold housing parts together. The bearing seat may be closed and seamless.
The squeeze elements furthermore allow a certain change of angle of the bearings, so that it is readily possible to provide bearing seats for bearings of a shaft on different housing parts. Centering means preferably can be provided, which at least approximately assure an alignment of the bearing seats.
The squeeze regions can be disposed at equal circumferential intervals. If a load absorbing preferential direction is desired, then the spacings also can be defined as unequal, for instance being placed closer together in the load-absorbing direction.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which: